Ventilated Roof Apparatus and Method

ABSTRACT

In ventilating a roof, an eave vent and a ridge vent are provided. The eave vent and ridge vent each is equipped with a fabric filter. The fabric filter is not waterproof and is wettable and hence self-cleaning. The permeability to air of the eave vent fabric filter is less than that of the ridge vent fabric filter and the resistance to air flow of the eave vent is greater than that of the ridge vent. The attic space under the roof acts as a manifold, distributing low pressure throughout the attic space.

I. RELATED APPLICATIONS

This application is related to and claims priority from provisionalapplication No. 61/337,855 filed Feb. 12, 2010 by the inventor namedherein.

II. BACKGROUND OF THE INVENTION

A. Field of the Invention

The Invention is an apparatus for ventilating a roof, a roof ventilatedusing the apparatus of the invention and a method of ventilating a roofusing the apparatus.

B. Statement of the Related Art

Moisture trapped in an attic or other space underneath the pitched roofof a structure can damage the roof, can damage the remainder of thestructure and can promote growth of mold within the attic. To avoidthese effects, the space underneath the roof must be ventilated.

As used in this document, the term ‘attic’ refers to an attic and alsorefers to any other air space under a roof, such as the space between aceiling or insulation and a roof deck of a structure equipped with acathedral ceiling.

During daylight hours, the sun shining on the roof warms the roof deck,causing the roof deck to be warmer than the ambient air. The warm roofdeck warms the air within the attic. During cold weather, heat withinthe inhabited space of the structure will leak into the attic space,which also warms the air in the attic space. The warm air within theattic space expands, becomes buoyant, and tends to rise. Because theroof is pitched, the warm air rises toward the ridge of the roof. Thewarm air can be released from the ridge by a ridge vent.

Warmed air escaping from the vent will place the attic space at a lowerair pressure than the ambient pressure outside the attic. For effectiveventilation, eave vents are provided to allow make-up ambient air toenter the area under the roof. If any portion of the roof is starved forventilation air, then the lack of air flow through the air-starved atticspace may allow the evils of inadequate ventilation to occur.

A roof equipped with eave and ridge vents acts as a large, low-pressureair pump, pumping air out through the ridge vent and in through the eavevents. The power input to the roof air pump system is heat energygenerated either by sunlight shining on the roof deck or by heat leakinginto the attic from the heated living space of the structure.

The ridge and eave vents must provide both an avenue for escape andentry of the air and also must prevent the entry of moisture in the formof rain or snow into the attic space. To that end, a ridge vent or aneave vent may feature a fabric filter. The prior art fabric filtergenerally is selected to be water proof and to prevent rain or snow fromentering the vent while allowing air to pass through the fabric.

Because the flow of air through the attic is generally from the eavevent to the ridge vent, dust or dirt in the air moving through the atticcan be trapped on the side of the fabric filter of the ridge vent thatis toward the attic. The result is that the ridge vent can becomeblinded over time.

Blinding of the fabric filter is less of an issue for an eave vent,since dust and dirt will tend to collect on the side of the fabricfilter that is toward the outside of the structure. Provided that thefabric filter is located so as to expose the fabric filter to theweather, rain water may wash the dust and dirt from the fabric filter ofthe eave vent, preventing the fabric filter from becoming blinded.

The present invention is not taught by the prior art.

III. SUMMARY OF THE INVENTION

The invention is an apparatus for ventilating an attic or other areaunder a roof. The invention also is a roof ventilated using theapparatus and a method of ventilating a roof. The apparatus is a ridgevent, an eave vent, and a combination of the ridge and eave vents. Theridge vent may be a two-sided ridge vent.

As used in this document, the term ‘eave’ generally means the horizontalroof edge of a pitched roof. The ‘eave’ is generally the lowest locationon a pitched roof deck. As used in this document, the term ‘eave vent’includes a vent in a soffit located below a roof deck and also includesa top vent communicating through the top side of the roof deck fromabove. The ‘eave vent’ generally is located proximal to the eave, but inthe case of the top vent may be located anywhere on the roof below theridge vent.

As used in this document, the term ‘ridge’ means the locations on apitched roof defined by intersecting planes of the roof deck and thatdefine an included angle of less than 180 degrees. The ‘ridge’ generallyis the highest location on the roof, unless the roof utilizes the hiproof design, in which event the ‘ridge’ may slope from the peak of theroof to the eave. As used in this document, a ‘ridge vent’ is locatedproximal to the ridge, including the sloping ridges of a hip roof.

A primary goal of any roof ventilation system is to provide ventilationto the attic or other entire area under the roof. As noted above, ifflow paths through a portion of an attic do not exist, that portion ofthe attic will not be ventilated. If flow paths exist, but if other flowpaths present inadequate resistance to air flow, the air will take theflow path of low resistance. The remainder of the roof that has a higherresistance to air flow will be starved for ventilation air and willsuffer the evils associated with inadequate ventilation, as describedabove.

The apparatus, method and roof of the invention achieve more evenventilation of the attic space by adjusting the air flow resistance ofthe eave and ridge vents. The resistance to air flow is adjusted so thatthe resistance to air flow presented by the sum of the ridge vents isless than the resistance to air flow presented by the sum of the eavevents supplying the ridge vents. The entire attic space thereforeoperates at a negative pressure when the air in the attic is warmed,which negative pressure no one region of the eave vents can relieve. Thevolume of the attic therefore acts as a large manifold, conveying thatnegative air pressure to every corner of the attic.

Eave vents are provided in all areas of the roof, providing paths forambient air to enter the attic. The resistance to air flow of the eavevents is selected to allow entry of ventilation air but not to allow somuch air to enter that the negative pressure under the roof is relievedat any location. The resistance to air flow of the eave vents isselected to be substantially greater than the resistance to air flow ofthe ridge vent because, for a pitched roof, the length of the eaves fora roof generally is considerably greater than the length of the ridge.The length of the eave vents therefore generally is much greater thanthe ridge vents.

Both the ridge vent and the eave vent are composed of a corrugatedplastic. The corrugations of the plastic define multiple elongatedchannels through which air passes.

The eave vent features an eave vent intake opening defined by the openends of the multiple elongated channels that are exposed to the airoutside the roof. The eave vent also features an eave vent dischargeopening exposed to the air in the attic through a roof deck vent openingproximal to the eave.

The ridge vent features a ridge vent discharge opening that is exposedto the air outside the attic and defined by the open ends of themultiple elongated channels. The ridge vent also features a ridge ventintake opening communicating through the roof deck at a roof deck ridgeopening proximal to the ridge. The discharge opening of the ridge ventand the intake opening of the eave vent are defined by the open ends ofthe multiple elongated channels defined by the corrugated plastic.

A fabric filter covers the discharge opening of the ridge vent and theintake opening of the eave vent. The fabric filter is composed of afabric that wraps about each of the soffit and the ridge vent and isattached to both the top and the bottom of the soffit and of the ridgevent. Any suitable attachment means may be utilized, such as an adhesivebond or a thermal weld.

The fabric of the fabric filter is selected to allow water to passthrough the fabric. The fabric is wettable and allows moisture to wickthrough the fabric and to wet both sides of the fabric, while preventingsubstantially all droplets of water from traveling through the fabric.Water that has passed through the fabric moves by gravity from the topto the bottom of the fabric. In so doing, the water entrains and carriesoff dust collected on both the inside and outside surfaces of thefabric. The fabric therefore allows the water to wash the dust from boththe inside and the outside surfaces of the fabric, preventing blindingof the fabric filter.

Location of the fabric filter on the outside of the channels defined bythe corrugated plastic prevents water that passes through the fabricfrom entering the attic space. Because the fabric filter is located atthe outside end of the elongated channels defined by the corrugatedplastic, any water passing through the fabric must travel the length ofthe elongated channels to reach the attic. Because the roof is pitchedand because the elongated channels also are pitched to conform to theroof deck, that water is required to run up hill. Water penetrating thewettable fabric therefore does not enter the attic.

Attachment of the fabric filter to both the top side and the bottom sideof the ridge vent or eave vent allows convenient handling andinstallation of the fabric filter. Installation of the ridge or eavevent involves nailing through the vent from the top side to the bottomside. Some of the nails penetrate the fabric that is wrapped about thetop side and the bottom side of the vent, mechanically securing the twoends of the fabric to the roof. The mechanical connection of the fabricto the roof allows the fabric to withstand high winds without failure.

The resistance to air flow of the ridge vent and the eave vent isdetermined by the friction of air passing through the channels and bythe air permeability of the fabric filter for each of the eave vent andthe ridge vent. The dimensions of the eave vent and the ridge vent, andhence the friction of the air passing through the channels, areconstrained by practical and aesthetic considerations. Thoseconsiderations include that the channels cannot be so large as to allowrain or snow to enter the attic space and cannot be so small as toeasily blocked, as by leaves and debris. The aesthetic considerationsinclude the appearance of the vent on the roof. The dimensions of thechannels therefore do not allow extensive adjustment of the resistanceto air flow of the vents.

Nonetheless, resistance to air flow can be readily adjusted by selectinga fabric filter having an appropriate permeability to air; namely, theresistance to air flow per unit area of the fabric. Selecting a fabricfilter for the eave vent that has a low permeability relative to that ofthe ridge vent allows the air pressure within the attic to remainadequately low so that the attic acts as a manifold, drawing ventilationair through all of the eave vents and while providing adequateventilation to the entire attic space.

The apparatus, method and roof of the invention provide that the fabricfilter of the eave vents is selected so that the permeability of thesoffit filter fabric is less than the permeability of the ridge ventfilter fabric.

The apparatus, method and roof of the invention is particularly usefulfor ventilating roofs that previously have been difficult to ventilatewithout excess water penetration, such as hip roofs.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross section of a ventilated roof.

FIG. 2 is a schematic representation of air flow through the roof.

FIG. 3 is a cross section of a ridge vent in place on the roof deck.

FIG. 4 is a perspective view of the ridge vent of FIG. 3.

FIG. 5 is a cross section of an eave vent in place on a roof deck.

FIG. 6 is a perspective view of the eave vent of FIG. 5.

FIG. 7 is a perspective view of a roof deck.

FIG. 8 is a perspective view of the roof deck with an eave vent inplace.

FIG. 9 is a perspective view of the roof deck in the process ofinstalling shingles and the ridge vent.

FIG. 10 is a perspective view of the completed roof.

V. DESCRIPTION OF AN EMBODIMENT

The invention is an apparatus and method for ventilating an attic spaceor other area under a roof. As illustrated by FIGS. 1 and 7 through 10,a roof deck 2 covers a structure 4. The structure 4 features an atticspace 6 beneath the roof deck 2. As used in this document, the term‘attic space’ also includes any area under a roof, such as the spacebetween the ceiling and a roof deck 2 of a room having a cathedralceiling. The roof deck 2 is pitched as illustrated by FIGS. 1 and 7through 10, meaning that the roof deck 2 defines an adequate angle withthe horizontal to allow the use of shingles 12. The roof deck 2 iscomposed of any suitable planar material, such as plywood or metalsheets. The roof deck 2 defines a ridge 8 at its highest location and aneave 10 at a location lower than the ridge 8.

As illustrated by FIGS. 1, 3, 4, 9 and 10, the roof includes a ridgevent 14 covering a roof deck ridge vent opening 16 located at the ridge8 of the roof deck 2. The roof also includes an eave vent 18 covering aroof deck eave vent opening 20 located proximal to the eave 10. The eavevent 18 and roof deck eave vent opening 20 may be at any location on theroof deck 2 below the elevation of the ridge 8 and ridge vent 14.

The eave vents 18 illustrated by the drawings are of the top vent typeand communicate with the attic space 6 through the eave vent opening 20from above the roof deck 2. This description of an embodiment appliesequally to an eave vent 18 of the soffit vent type that communicateswith the attic space 6 through the soffit from below the roof deck 2.

As shown by FIG. 1, air 22 within the attic space 6 is warmed by the sunshining on the roof deck 2 or by heat from the inhabited space of thestructure 4. The air 22 expands due to the increased temperature. Thewarmed air 22 is more buoyant than other air 22 within the attic space 6and rises within the attic space 6 until the air reaches the ridge 8.The warmed air 22 flows through the ridge vent opening 16 and throughthe ridge vent 14. Make-up air 22 flows from outside the attic space 6through the eave vent 18 and through the roof deck eave vent opening 20into the attic space 6. The ventilated roof, including the eave vent 18,the eave vent opening 20, the attic space 6, the roof deck 2, the ridgevent opening 16 and the ridge vent 14 comprises a heat-powered air pump,pumping air 22 out through the ridge vent 14 and in through the eavevent 18.

FIG. 2 is a schematic diagram illustrates the air pressure and flowrelationships of the ventilated roof. Heated air 22 flows out of theattic space 6 through ridge vent 14 due to the buoyancy of the heatedair 22. The departure of the heated air 22 through the ridge vent 14reduces the air pressure within the attic space 6. The reduced airpressure within the attic space 6 causes cool make-up air 22 to flowthrough the eave vents 18 due to the higher air pressure outside theattic space 6. The cool air 22 is warmed within the attic space 6,becomes buoyant and rises to the ridge vent 14, repeating the process.

All areas of the roof are equipped with eave vents 18, as indicated bythe four schematic eave vents 18 of FIG. 2. The flow of air 22 at anyone location on an eave vent 18 is determined by the air pressuredifferential across the eave vent 18 and coupled with the resistance toair flow presented by the eave vent 18. The air pressure differentialacross a portion of an eave vent 18 is determined by factors thatinclude the buoyancy of the air 22 exiting the ridge vent 14, whetherthe portion of the roof deck 2 above the eave vent is subject to directsunlight, the resistance of all of the other portions of eave vent andthe length of the flow path from the eave vent 18 to the ridge vent 14.

Air 22 flowing into the attic space 6 will follow the path of leastresistance. If one (or more) of the eave vents 18 presents an adequatelylow resistance to air flow coupled with a short flow path while othereave vents 18 present a higher resistance to air flow coupled with alonger flow path, the portions of the eave vents 18 with very lowresistance and hence a relatively high air flow may relieve the pressuredifference between the inside and outside of the attic space 6. Theportions of the attic space 6 served by the eave vent 18 having a higherresistance and a longer flow path then will see little, if any, airflow.Portions of the attic space 6 then are starved of ventilation air 22 andmay suffer from all of the ill effects of inadequate ventilation.

The airflow can be more evenly distributed among the eave vents 18,assuring more even ventilation of all areas of the roof, if theresistance to airflow of each eave vent 18 is adequately high so thatthe attic space 6 acts as a manifold, distributing the relatively lowpressure to all areas of the attic space 6.

FIGS. 3 through 6 illustrate construction of the ridge vent 14 and theeave vent 18 to achieve more even distribution of ventilation air 22within the attic space 6. FIG. 3 is a cross section of a ridge vent 14installed on a roof deck 2. Roof deck 2 defines a pitched roof and isclad with shingles 12. Ridge vent 14 is composed of corrugated plasticpanels 28. Each corrugated plastic panel 28 comprises two planar plasticlayers with a corrugated plastic layer in between, similar in appearanceto familiar corrugated cardboard. The corrugated plastic 28 panelsdefine a plurality of channels 30. The plurality of channels communicatebetween a ridge vent opening 24, also referred to herein as the ‘ridgevent discharge opening 24,’ that is in contact with air 22 outside ofthe ridge vent 14 and a ridge vent intake opening 31 on the underside 32of the ridge vent 14. The ridge vent intake opening 31 is incommunication with the roof deck ridge vent opening 16, which is incommunication with the air 22 within the attic space 6.

The ridge vent opening 24 is equipped with a ridge vent fabric filter 34that covers the ridge vent opening 24. As shown by the detail cutawaydrawing of FIG. 4, the ridge vent fabric filter 34 is wrapped about thetop 36 and the bottom 38 of the ridge vent 14 and secured to the top 36and bottom 38 of the ridge vent 14 by an adhesive bond or by thermalwelding.

As shown by FIG. 3, wrapping of the fabric filter 34 about the top 36and bottom 38 of the ridge vent 14 allows the fabric filter 34 to besecured to ridge vent 14 and to the roof deck 2 by nails 40 when theridge vent 14 and shingles 12 are installed.

The size of ridge vent opening 24, and hence the area of the ridge ventavailable to allow heated air 22 to escape, is constrained by aestheticconsiderations of the appearance of the finished roof. Three layers ofcorrugated plastic panels 28, totaling about three quarters of an inchin thickness, has proven acceptable in practice.

The construction of the eave vent 18 is illustrated by FIGS. 5 and 6.The eave vent 18 also is composed of corrugated plastic panels 28defining a plurality of eave vent channels 30. The channels communicatebetween an eave vent opening 26, also referred to herein as the ‘eavevent intake opening 26,’ and an eave vent discharge opening 50 on theeave vent bottom 48. The eave vent opening 26 is on the outside of theeave vent and in contact with air 22 outside the attic space 6. The eavevent discharge opening 50 is in communication with a roof deck eave ventopening 20 that communicates through the roof deck 2 to the attic space6. The thickness of the eave vent opening 26 is driven in part byaesthetic considerations and in part by resistance to moisturepenetration. Three layers of corrugated plastic panels 28, totalingabout three quarters of an inch in thickness, have proven suitable inpractice.

The eave vent 18 is wedge-shaped. To maintain the wedge-shape whileallowing ventilation air 22 to move through the eave vent 18, an eavevent support 42 intermediate between the eave vent opening 26 and theroof deck eave vent opening 20 is provided. The eave vent support 42 iscomposed of a second plurality of layers of corrugated plastic panels28. The number of panels 28 making up the eave vent support 42 is lessthan the number of panels making up the eave vent opening 26 to allowthe eave vent 18 to be wedge-shaped when installed on a roof deck 2. Athickness of two corrugated plastic panels 28 have proven suitable inpractice for the eave vent support 42.

An eave vent fabric filter 44 covers the eave vent opening 26. The eavevent filter fabric 44 is wrapped about the eave vent top 46 and the eavevent bottom 48. The wrapping of the eave vent fabric filter 44 about thetop 46 and bottom 48 provide that nails 40 will secure the filter fabric44 to the eave vent 18 and the eave vent 18 to the roof deck 2 when theeave vent 18 is installed.

The ridge vent fabric filter 34 and the eave vent fabric filter 44 eachhas a permeability to air flow. The resistance of the ridge vent 14 andthe eave vent 18 to the passage of air 22 is a function of the size(thickness and length) of the ridge vent opening 24, the friction of theair 22 moving through the channels 30 of the ridge 14 and soffit 18vents and the permeability to air flow of the ridge vent fabric filter34 and the permeability to air flow of the eave vent fabric filter 44.The less permeable the fabric filters 34, 44, the higher the resistanceto air flow and the less air 22 that can flow through the vent 14, 18for a given air pressure differential.

The resistances to air flow of the ridge vent 14 and the eave vent 18therefore can be selected by selecting appropriate fabric filters 34,44. The fabric filters 34, 44 are selected so that the permeability ofthe eave vent fabric filter 44 is less than the permeability of theridge vent fabric filter 34. For ridge and eave vents 14, 18 havingapproximately the same total area for the eave vent opening 26 and theridge vent opening 24, selecting fabric filters 34, 44 when thepermeability of the eave vent fabric filter 44 is less than that of theridge vent fabric filter 24 provides that the entire attic space 6 ismaintained at a reduced air pressure when the ventilation system is inoperation to ventilate the roof and provides that no portion of theattic space 6 is starved for ventilation air. In short, the entire atticspace 6 acts as a manifold and distributes the reduced air pressure toall of the eave vents 18.

The fabric filter 34, 44 is selected to be wettable for the purposes ofwashing accumulated dust from otherwise inaccessible fabric filter 34,44 surfaces. The wettable fabric selected for the fabric filters 34, 44is not waterproof and allows water from rain or snow to move through thefabric filters 34, 44 from the outside of the ridge and eave ventopenings 24, 26. The water runs down the inside surfaces of the fabricfilters 34, 44 due to gravity, rinsing accumulated dust from the fabricfilters 34, 44. The use of a non-waterproof, wettable fabric for fabricfilters 34, 44 allows both sides of the fabric filters 34, 44 to becleaned by water from rain or snow. The water is prevented from enteringthe attic space 6 or from otherwise entering the structure 4 by theuphill journey through the multiple channels 30 that the water wouldhave to travel to reach the attic space 6 (see FIGS. 3 and 6).

The wettable fabric that has proven successful in practice is Colback®TD series by Colbond, Inc., P.O. Box 1057, Enka, N.C. 28728. Colbond,Inc is a division of Low & Bonar PLC, a publicly traded UK corporationdomiciled in Scotland. The Colback® fabric is a spunlaid, nonwovenfabric made from bicomponent filaments having a polyester core and anylon 6 skin. The fibers are thermally bonded to form the fabric. Thepermeability to air of the fabric varies as does the weight of thefabric. The applicant believes that a fabric having a weight of 100grams per square meter is suitable for the fabric filter 44 covering theeave vent opening 26. The applicant believes that a fabric having aweight of 30 to 50 grams per square meter is suitable for the fabricfilter 34 covering the ridge vent opening 24. The fabric is selected tobe black or dark gray in color for maximum heat absorption and toaesthetically blend in with the appearance of the roof.

FIGS. 7 through 10 illustrate installation of the apparatus of theinvention. FIG. 7 is a roof deck 2 of a structure 4, such as a building.The roof deck 2 has a top side 52 and includes an eave 10 and a ridge 8.The roof deck also includes a roof deck eave vent opening 20 proximal tothe eave 10 and a roof deck ridge opening 16 proximal to the ridge 8.The roof deck 2 is pitched.

FIG. 8 illustrates location of the eave vent 18 on the roof deck 2. Theeave vent 18 is located proximal to the eave 10 and is located so thatthe eave vent discharge opening 50 is in communication with the roofdeck eave vent opening 20. An end cap 54 tapers the eave vent 18 to theroof deck 2 and prevents breakage of shingles 12.

FIG. 9 illustrates the relative location of the eave vent 18, shingles12, roof deck 2 and ridge vent 14. In FIG. 9, the eave vent 18, shingles12 and ridge vent 14 are in the process of being installed. The shingles12 cover the eave vent 18 and end cap 54. The ridge vent 14 overlays thetop course of shingles 12 and covers the roof deck ridge vent opening 16so that the ridge vent opening 24 on the outside of the ridge vent 14 isin communication through the ridge vent 14 to the roof deck ridge ventopening 16. The ridge vent 14 is two-sided, in that ridge vent openings24 appear on both sides of the ridge 8. Ridge vent fabric filter 34wraps about the ridge vent 14 and covers ridge vent opening 24.

FIG. 10 illustrates the roof with eave vents 18, ridge vent 14 andshingles 12 installed. Eave vent 18 is flanked by end caps 54 andcovered by shingles 12. Eave vent opening 26, covered by eave ventfabric filter 44, is exposed to air 22 outside the attic space 6 ofstructure 4. The roof deck 2 is covered by shingles 12. The roof deckridge vent opening 16 is covered by ridge vent 14. Ridge vent 14 also iscovered by shingles 12. Ridge vent opening 24 is covered by ridge ventfabric filter 34 and is exposed to the air 22 outside the attic space 6.Air 22 enters the attic space 6 through the eave vent opening 26, passesthrough the attic space 6 and exits the attic space through the ridgevent opening 24. The flow of air is controlled by selecting the eavevent fabric filter 44 and the ridge vent fabric filter 34 so that thepermeability to air of the eave vent fabric filter 44 is less than thatof the ridge vent fabric filter 34. The resistance to air flow of theeave vent 18 therefore is greater than the resistance to air flow of theridge vent 14.

LIST OF NUMBERED ELEMENTS

The following are indicated as numbered elements on the drawings.

-   a roof deck 2-   a structure 4-   an attic space 6-   a ridge 8-   an eave 10-   shingles 12-   a ridge vent 14-   a roof deck ridge vent opening 16-   an eave vent 18-   a roof deck eave vent opening 20-   air 22-   A ridge vent opening 24-   An eave vent opening 26-   a corrugated plastic 28-   a plurality of channels 30-   a ridge vent discharge opening 31-   an underside of the ridge vent 32-   a ridge vent fabric filter 34-   a top of the ridge vent 36-   a bottom of the ridge vent 38-   a nail 40-   an eave vent support 42-   an eave vent fabric filter 44-   an eave vent top 46-   an eave vent bottom 48-   an eave vent discharge opening 50-   a roof deck top side 52-   an end cap 54

1. An apparatus, the apparatus comprising: a. a roof deck, said roofdeck being located on a structure, said roof deck covering an atticspace, said roof deck being pitched, said roof deck having a ridge andan eave; b. a ridge vent located proximal to said ridge, said ridge ventdefining a ridge vent opening, said ridge vent opening being incommunication with said attic space through said roof deck; c. an eavevent, said eave vent being located at said eave, said eave vent definingan eave vent opening, said eave vent opening being in communication withsaid attic space through said roof deck, said ridge vent defining aridge vent resistance to an air flow, said eave vent defining an eavevent resistance to said air flow, said eave vent resistance to said airflow being greater than said ridge vent resistance to said air flow. 2.The apparatus of claim 1 wherein said ridge vent and said eave vent arecomposed of a corrugated plastic, said corrugated plastic defining aplurality of channels, said plurality of channels of said ridge ventdefining said ridge vent opening, said plurality of channels of saideave vent defining said eave vent opening.
 3. The apparatus of claim 2,further comprising: a. a ridge vent fabric filter, said ridge ventopening being disposed on an outside of said ridge vent, said ridge ventfabric filter covering said ridge vent opening, said ridge vent fabricfilter having a ridge vent fabric permeability to air; b. an eave ventfabric filter, said eave vent opening being disposed on an outside ofsaid eave vent, said eave vent fabric filter covering said eave ventopening, said eave vent fabric filter having an eave vent fabricpermeability to air, said eave vent permeability to air being less thansaid ridge vent permeability to air.
 4. The apparatus of claim 3 whereinsaid ridge vent fabric filter is composed of a wettable fabric.
 5. Theapparatus of claim 4 wherein said ridge vent defining a ridge vent topand a ridge vent bottom, said ridge vent fabric filter extending fromsaid ridge vent top to said ridge vent bottom, said ridge vent fabricfilter being secured to said ridge vent top and to said ridge ventbottom by a one of an adhesive bond and a thermal weld, said eave ventdefining an eave vent top and an eave vent bottom, said eave vent fabricfilter extending from said eave vent top to said eave vent bottom, saideave vent fabric filter being secured to said eave vent top and to saideave vent bottom by a one of said adhesive bond and said thermal weld.6. The apparatus of claim 5 wherein said eave vent opening is composedof a first plurality of layers of said corrugated plastic, said eavevent defining an eave vent support, said eave vent support beingcomposed of a second plurality of layers of said corrugated plastic,said first plurality being greater than said second plurality, saidcorrugated plastic of said eave vent support defining a plurality ofsaid channels, said eave vent opening being in communication with saidattic space through said channels defined by said eave vent support. 7.An eave vent apparatus, the eave vent apparatus comprising: a corrugatedplastic, said corrugated plastic defining a plurality of channels, saidplurality of channels defining an eave vent intake opening, said eavevent having a bottom side, said bottom side of said eave vent openingdefining an eave vent discharge opening, said eave vent intake openingbeing in communication with said eave vent discharge opening, said eavevent being configured so that said plurality of channels defining saideave vent intake opening are in communication with an attic space whensaid eave vent is mounted to a top side of a roof deck having a ridgeand an eave and said eave vent discharge opening is in communicationwith a roof deck eave vent opening proximal to said eave, said eave venthaving an eave vent resistance to air flow, said eave vent resistance toair flow being selected so that said eave vent resistance to said airflow is greater than a ridge vent resistance to said air flow when saideave vent is mounted in communication with said roof deck eave ventopening and said ridge vent is mounted in communication with a roof deckridge opening proximal to said ridge.
 8. The apparatus of claim 7, theapparatus further comprising: A soffit fabric filter, said eave ventopening being disposed on an outside of said eave vent, said eave ventfabric filter covering said eave vent opening, said eave vent fabricfilter having an eave vent fabric permeability to air, said eave ventpermeability to air being less than a permeability to air of a ridgevent fabric filter when said eave vent is mounted in communication withsaid roof deck eave vent opening and said ridge vent is mounted incommunication with said roof deck ridge opening, and said ridge vent hasa discharge opening covered by said ridge vent fabric filter.
 9. Theapparatus of claim 8 wherein said eave vent fabric filter is composed ofa wettable fabric.
 10. A ridge vent apparatus, the ridge vent apparatuscomprising: a corrugated plastic, said corrugated plastic defining aplurality of channels, said plurality of channels defining a ridge ventdischarge opening, the ridge vent apparatus having a bottom side, saidbottom side of the ridge vent apparatus defining a ridge vent intakeopening, said ridge vent intake opening being in communication with saidridge vent discharge opening, said ridge vent intake opening being incommunication with an attic space when said ridge vent is mounted to aridge of a roof deck and said ridge vent intake opening is incommunication with a roof deck ridge opening in said roof deck, saidridge vent having a ridge vent resistance to air flow, said ridge ventresistance to air flow being selected so that said ridge vent resistanceto said air flow is less than an eave vent resistance to said air flowwhen said ridge vent is mounted to said roof ridge and said eave vent ismounted in communication with said attic space proximal to an eave ofsaid roof deck.
 11. The apparatus of claim 10, the apparatus furthercomprising: A ridge vent fabric filter, said ridge vent dischargeopening being disposed on an outside of the ridge vent apparatus, saidridge vent fabric filter covering said ridge vent discharge opening,said ridge vent fabric filter having a ridge vent fabric permeability toair, said ridge vent permeability to air being greater than apermeability to air of an eave vent fabric filter when said ridge ventis mounted to said ridge of said roof deck, and said eave vent ismounted in communication with said attic space proximal to said eave,and said eave vent has an intake opening covered by said eave ventfabric filter.
 12. The apparatus of claim 11 wherein said ridge ventfabric filter is composed of a wettable fabric.
 13. A method forventilating a roof, the method comprising: a. providing a ridge vent,said ridge vent being composed of a corrugated plastic, saidcorrugations defining a plurality of ridge vent channels, said pluralityof ridge vent channels defining a ridge vent discharge opening, saidbottom of said ridge vent defining a ridge vent intake opening, saidridge vent having a resistance to air flow from said ridge vent intakeopening to said ridge vent discharge opening; b. installing said ridgevent, the roof defining a roof deck having a ridge and an eave anddefining an attic space, said roof defining a roof deck ridge openingproximal to said ridge, said roof deck ridge opening communicatingthrough said roof deck, said ridge vent being installed so that saidridge vent intake opening is located in communication with said atticspace through said roof deck ridge opening; c. providing an eave vent,said eave vent being composed of said corrugated plastic, saidcorrugated plastic defining a plurality of eave vent channels, saidplurality of eave vent channels defining an eave vent intake opening,said eave vent having a bottom side, said eave vent bottom side definingan eave vent discharge opening, said eave vent intake opening being incommunication with said eave vent discharge opening, said eave venthaving an eave vent resistance to air flow from said eave vent intakeopening to said eave vent discharge opening, said eave vent resistanceto air flow being greater than said ridge vent resistance to air flow;and d. installing said eave vent proximal to said eave of said roofdeck, said eave vent discharge opening being in communication with saidattic space.
 14. The method of claim 13 wherein said ridge vent includesa ridge vent fabric filter, said ridge vent fabric filter beingconfigured to cover an outside of said ridge vent discharge opening,said ridge vent fabric filter having a ridge vent permeability to air,said eave vent including an eave vent fabric filter, said eave ventfabric filter being configured to cover an outside of said eave ventintake opening, said eave vent fabric filter having an eave ventpermeability to air, said ridge vent permeability to air being greaterthan said eave vent permeability to air.
 15. The method of claim 14wherein said ridge vent has a ridge vent top side, said ridge ventfabric filter extending from said ridge vent top side to said ridge ventbottom side, said ridge vent fabric filter being attached to said ridgevent top side and to said ridge vent bottom side by a one of an adhesivebond and a thermal weld, and wherein said eave vent has an eave vent topside, said eave vent fabric filter extending from said eave vent topside to said eave vent bottom side, said eave vent fabric filter beingattached to said eave vent top side and to said eave vent bottom side bysaid one of said adhesive bond and said thermal weld.
 16. The method ofclaim 15 wherein said ridge vent fabric filter and said eave vent fabricfilter are composed of a wettable fabric.
 17. The method of claim 16wherein said ridge and said eave of said roof each has a length, saidridge vent has a length and said eave vent has a length, said length ofsaid ridge vent is selected to occupy substantially all of said lengthof said ridge, said length of said eave vent is selected to occupysubstantially all of said length of said eave.